Water-insoluble, water-permeable bag having a water-soluble or water-dispersable protective layer and containing a particulate detergent composition

ABSTRACT

A detergent product comprises a water-insoluble, water-permeable bag containing a particulate detergent composition, the bag material having a water-soluble or removable water-insoluble layer to protect the bag material from the composition and to reduce dusting. The protective layer may be coated on or impregnated into the bag material or may form a continuous layer laminated to the inside of the bag material or may be in the form of a separate inner bag. The water-soluble material may be soluble polyvinyl alcohol, polyethylene glycol, polysaccharide, alkali metal silicate, soap, nonionic detergent, gelatine, salts or esters of alginic acid. The removable water-insoluble material may be a silicone, a fatty acid, a water-insoluble cationic fabric softener, polyvinylacetate, insoluble polyvinyl alcohol, clay, zeolite, calcite, silica, titania or a wax. The bag material may be paper and/or plastics material such as polypropylene. The detergent composition is a fully formulated composition or other fabric treatment material.

TECHNICAL FIELD

This invention relates to detergent products which are suitable forfabric washing and which contain detergent compositions in particulateform.

BACKGROUND ART

Although the marketing of particulate detergent compositions packaged incartons is common practice, this imposes constraints both on theirformulation and methods of production. For example the compositions mustbe free flowing and have an attractive appearance to the consumer, andthe ingredients should not segregate during transport and storage. Theproducts must also be safe, both for contact with the skin and in theevent of accidental ingestion; in particular, the compositions shouldnot contain too high a level of alkaline materials, although alkalinityis beneficial for detergent properties.

When using washing machines which have a rotating drum in which thefabrics are placed, there can also be substantial losses ofconventionally dosed detergent powder by retention in the dispenser andby its accumulation in the dead spaces beneath the drum, such as thedrain hose.

It has been proposed previously to market powdered detergentcompositions in packages, each of which contain suitable amounts of thedetergent powders for individual washes under standard washingconditions. In particular, from British Pat. No. 1,298,454 and U.S. Pat.No. 3,198,740 the detergent powders can be contained within bags ofwater-permeable or water-soluble materials, such as soluble polyvinylalcohol, but such packages have not yet met with much commercialsuccess. One of the reasons for this, in the case of water-soluble bags,is the sensitivity to moisture which leads to storage difficulties. Inthe case of water-permeable materials, one of the reasons is thedifficulty of making the bags sufficiently permeable to water in use sothat the contents of the bags are rapidly dissolved out into the washliquor, and yet reducing dusting of the detergent powder out of the bagsduring transport and manual handling to an acceptable level. Also, somedetergent compositions, in particular bleach-containing compositions,cause inacceptable degradation of the bag material.

Canadian Patent No. 901 244 discloses a bag for insecticide powders, thebag being formed of a water-soluble film reinforced with a net ofwater-insoluble thermoplastic material.

DISCLOSURE OF THE INVENTION

According to the invention there is provided a detergent productcomprising a particulate detergent composition contained within a closedwater-insoluble, water-permeable bag formed of sheet material, a layerof water-soluble or removable water-insoluble material protecting thebag material from the detergent composition. By using this form ofconstruction for the bag, it is possible to protect the bag materialduring storage and to prevent undue dusting of the composition throughthe bags and yet the porosity of the water-insoluble sheet material canbe high enough to quickly release all of the contents of the bag as soonas the water-soluble layer is dissolved or the water-insoluble layer isremoved in use. It is possible to use a relatively open water-insolublesheet material for the bag, as dusting of the detergent compositionthrough the pores is reduced or prevented by the water-soluble orremovable water-insoluble layer. Moreover, it is possible to form thebags of material which can be readily heat-sealed, which facilitatesmanufacture.

BEST MODE OF CARRYING OUT THE INVENTION

The bags are formed with a water-insoluble sheet material which can beformed of paper or of woven, knitted or non-woven fabric, provided thateach of these should be water-insoluble and water-permeable. If the bagsare to be used for detergent powder which contains a bleaching agent,for example sodium perborate or sodium percarbonate, it is alsodesirable to form the bags of sheet material made fromoxidation-resistant fibres.

A suitable sheet material for forming the bags is water-permeable paperor non-woven fabric of high wet strength, weighing about 5 to 100,preferably 10 to 60 g/m², especially about 15 to 40 g/m², such as iscommonly used for packaging beverage powders and other foodstuffs, andsuitable sheet materials of this type are commercially available forexample from J R Crompton Bros Ltd of Bury, England. The fibrespreferably used for the sheet materials may be of natural or syntheticorigin and may be used alone or in admixture, for example polyamide,polyester, polyacrylic, cellulose acetate, polyethylene, polypropylene,PVC, PVdC (polyvinylidene chloride) or cellulosic fibres. If somecellulose pulp is used, it may be desirable to include a proportion oflong fibres such as Manila hemp, in order to improve the strength of thesheet material, and pliability, and reducing stiffness, thereby givingthe material a fabric-like appearance, and a binder may be necessary forincreasing wet strength. It is preferred to include at least aproportion of thermoplastic fibres, for example polypropylene fibres forincreasing resistance to chemical attack by any of the ingredients ofthe detergent compositions.

The layer of water-soluble or water-insoluble material may be either acontinuous layer or sheet of such material or a discontinuous layer. Inthe former case the continuous layer can be attached, i.e. laminated tothe water-insoluble sheet material, inside the sheet material of thebags, or it may be separate from the sheet material, so forming one baginside the other. Particularly in the laminated form of construction ofthe bags using a continuous layer or sheet of a water-soluble material,it is preferred to use a synthetic water-soluble polymer (homopolymer orcopolymer) such as soluble polyvinyl alcohol or polyethylene glycol.

Particularly if a water-soluble material is applied as a discontinuouscoating on the water-insoluble sheet material, a wider variety ofwater-soluble materials can be used to give a protective effect, forexample polysaccharides such as starch or dextrin, alkali metalsilicate, soap, gelatine, salts and esters of alginic acid, salts andesters of methyl cellulose, carboxymethyl cellulose and water-solublecationic fabric softeners or water-soluble synthetic polymers such aswater-soluble polyvinyl alcohol, polyethylene glycol or nonionicdetergent compounds.

The water-insoluble sheet material may alternatively be treated with aremovable water-insoluble protecting agent. This can either be anon-volatile liquid or solid material, of organic or inorganic nature,provided that it is substantially inert to the detergent system and canbe applied to the sheet material, before or after forming the bags, togive a protective effect. The removable water-insoluble protecting agentshould be water dispersible to that, in use, it is quickly removed fromthe bag material, thereby opening up the pores in the bag materialenabling fast dissolution and dispersion of the detergent composition inthe wash liquor. In this specification the term "removablewater-insoluble protecting agent" is to be construed accordingly.Specific protecting agents which may be mentioned are waxes which aresolid or highly viscous liquids at room temperature, and which can beapplied to the sheet material to form a protective coating over thefibrous surface. Such materials are dispersible in detergent washliquor, especially at elevated temperatures where they may then alsoexert a beneficial lather controlling effect. The waxes are well knowncommercially available substances. The waxes can be of natural orsynthetic origin and optionally halogenated to improve their chemicalstability.

Alternative protecting agents are silicones, fatty acids,water-insoluble cationic fabric softeners, polymeric materials such aspolyvinylacetate, insoluble polyvinyl alcohol and insoluble finelydivided inorganic material, such as natural clays or synthetic colloidalfiller substances such as zeolite, calcite, silica or titania, which canbe applied to the sheet material so as to coat the fibres and to someextent temporarily close the pores of the sheet material until itsaddition to water. Preferably, clays are used for this purpose, forexample kaolin, attapulgite, Fuller's Earth, bentonite, montmorilloniteand smectite clays. Some of the clays, especially the smectite clays,have a fabric softening action in the wash after their removal from thebags in the use.

Mixture of protecting agents may be used, especially mixtures of theliquid or waxy solids with the finely divided inorganic materials. Theformer can thereby assist the adhesion of the latter to the sheetmaterial to enhance the protective effect.

In the case of the coating material being a wax, it is preferablyapplied to the sheet material before it is formed into the bags bypassing the sheet material through a bath of wax or by spraying on thewax, either as a hot melt or preferably in solution or as an aqueousemulsion. The gravure printing process used for waxing paper, such asoperated by George Makin Limited, Manchester, England, is suitable forsuch process. The water or organic solvent used to apply the wax in thisway is later removed, for example by heating, and this facilitates themore uniform application of the wax to the sheet material at acceptablelevels. The particulate inorganic protecting agents such as clays shouldbe applied by coating, impregnating, padding or spraying on an aqueousorganic solvent suspension, or preferably in admixture with the liquidor waxy solid materials. In the case of a removable water-insolubleprotective agent, the amount thereof used is advantageously about 0.5%to about 50%, preferably about 1-20% by weight based on the sheetmaterial. These treatments also minimise dusting, and protect the bagmaterial from attack by the detergent compositions. If the layer ofwater-soluble or removable water-insoluble material is discontinuous itis preferably attached for support to the water-insoluble sheet materialand may be applied thereto by impregnation, saturation or coating.

When a sheet material is used coated with a discontinuous water-solubleor removable water-insoluble layer, the pore size of the coated sheetmaterial should be such that there is no excessive dusting of thedetergent composition through the material of the bags in the dry state,but preferably not so small that water cannot pass readily through thematerial forming the bags to disperse and dissolve the contents when theproduct is used. The preferred level of coating is thus a function ofthe pore size distribution of the uncoated bag material, the particlesize distribution of the detergent composition and the acceptable degreeof dusting. For optimum properties the degree of dusting is such that nomore than about 5%, by weight, preferably no more than about 1%, of thedetergent composition particles can pass through the coated sheetmaterial. With very fine powders, for example made by dry mixing, themaximum pore size of the treated sheet material must be very small,preferably so as to retain only detergent particles greater than about20 microns. With coarser grained detergent compositions the maximum poresize of the treated sheet material may be larger so as to retaindetergent particles greater than about 100 microns, e.g. about 500 up toabout 1000 microns, as appropriate. It may be noted that larger poresizes are generally better for dissolving powder quickly, but this putsmore constraints on the powder processing techniques which can be usedin order to avoid excessive dusting.

Where the bag material is water-permeable paper or non-woven fabric ofhigh wet strength weighing about 10 to about 60 g/m², or other materialhaving a similar pore size distribution, a coating thickness of fromabout 15 m/g² to about 45 g/m², advantageously about 30 g/m², ispreferred.

The bags can be formed from a single folded sheet formed into a tubularsection, or from two sheets of the material bonded together at theedges. For example, the bags can be sachets formed from single foldedsheets and sealed on three sides or from two sheets sealed on four sidesfor the preferred rectangular shape. Alternatively, the sheets can befolded like envelopes with overlapping flaps to be sealed. Other bagshapes or constructions, for example circular cushion shaped sachets orof tetrahedron form, may be used if desired. The bags may also bereinforced, if desired, to decrease the risk of leakage during handling,for example by adding an extra thickness of the sheet material where thebags are expected to be held or passing completely round the bags tohelp support the weight of detergent powder.

The bags may be sealed by heat-sealing, cold pressure sealing or with anadhesive. In the case of heat-sealing the bag material should contain atleast a minor proportion of a thermoplastic material, such aspolyproplene. Alternatively, the bag material may be coated with a layerof heat-sealable or pressure sealable material such as a vinylacetate/vinyl chloride copolymer.

To increase the rate of dispersion and dissolution of the detergentcomposition in the wash liquor, the bag may be adapted to open in thewash, for example by bursting at a weak seal or along a perforationline, by the disintegration of the bag material itself or by at leastone of the seals being formed with a water-soluble adhesive that willdissolve in the wash liquor. The invention is also applicable to bagsthat do not open in the wash.

Any detergent composition in particulate form can be packaged toadvantage in the product of the invention. As an alternative to a fullyformulated detergent composition (that is a composition containing atleast a surfactant and a builder) the bags may contain any one or moreof the following fabric treatment materials: bleaches such as sodiumperborate; bleach precursors such as tetraacetylethylene diamine (TAED);fabric softeners such as quaternary ammonium compounds, starch,perfumes, anti-bacterial agents; stain removing agents and the like. Itcan be of particular advantage to add fabric treatment materials to thewash in a bag while dosing a fully formulated detergent composition in aconventional manner, where the incorporation of the fabric treatmentmaterial in the fully formulated detergent composition may otherwise bedifficult. This is of particular importance in the case of perfumes,bleaches, bleach precursors and cationic fabric softening agents.

The fully formulated compositions which can be packaged to advantage inthe products of the invention are amply described in the literature, forexample in "Surface Active Agents and Detergents", Volumes I and II, BySchwartz, Perry and Berch.

However, the products of the invention are advantageously used fordetergents powders containing insoluble ingredients. Specific examplesof such ingredients include finely divided calcium carbonate, the use ofwhich is described in UK Pat. No. 1,437,950, and sodium aluminosilicateion-exchange materials as described in UK Pat. Nos. 1,429,143, 1,473,201and 1,473,202.

It is also advantageous to use the products of this invention withdetergent compositions containing bleach systems, particularlycontaining TAED and sodium perborate.

In addition, the detergent products of the invention are particularlysuited for detergent compositions of relatively high bulk density, i.e.over about 0.5 g/cc, preferably about 0.6 to 0.8 g/cc, up to a maximumof about 1 g/cc, above which there tends to be a reduction in the rateof water solubility or dispersibility. The use of high bulk densitycompositions makes it possible to decrease the size of the detergentbags whilst still containing enough particulate detergent composition tobe fully effective during use. This also enables the use of simpleprocessing techniques for the production of the detergent compositionsthemselves, e.g. granulation or dry mixing instead of traditional spraydrying techniques.

If desired, the sheet material used to form the bag can be marked ortagged so that it can be easily recognised amongst the washed fabrics,for example the material may be printed with a simulated fabric patternssuch as check or gingham. It can then either be discarded, or, ifdesired, it may be constructed of a suitable material to provide it witha secondary use, for example as a cleaning cloth.

If desired, the bags can be formed with more than one separatecompartment containing different detergent ingredients or the bags maybe formed in a conjoined manner, for example in a strip to facilitatedosing of different numbers of the bags as appropriate for the washconditions. The use of multi-compartment bags facilitates the use ofdetergent ingredients which would otherwise interact with otheringredients in detergent compositions, whilst avoiding encapsulation orother treatment to prevent contact between such ingredients in a singlecomposition.

For example one compartment may contain a fully formulated detergentfree of bleach while a second compartment may contain the bleach. Athird compartment may contain a fabric softener.

The invention is illustrated by reference to the following Examples inwhich parts and percentages are by weight except where otherwiseindicated.

EXAMPLES 1 to 3

Bags for detergent compositions were constructed with a laminatedconstruction, having a water-soluble polyvinyl alcohol sheet (HI-SELONC) of thickness 0.0015 inch inside water-insoluble sheet materials asfollows:

EXAMPLE 1--Manila hemp with viscose wet strength agent (21 g/m²).

EXAMPLE 2--Manila hemp fibres treated with Kymene/polymeric wet strengthagent and with a 20:80 vinyl acetate/vinyl chloride copolymer as heatsealing agent. Weight 27 g/m².

EXAMPLE 3--Highly porous polypropylene spun-bonded non-woven fabric.Weight 10 g/m².

All three types of bags were made by folding the superimposedwater-soluble and water-insoluble sheet materials (former inside) andthen heat-sealing along the two opposing edges. 84 g of a detergentcomposition of high bulk density (0.68 g/cc) prepared by a granulationprocess as described in Belgian Pat. No. 867 038 (U.S. application Ser.No. 905,681) to the formulation below was then added to the bags whichwere heat-sealed along the open edges to form sachets (41/2"×41/2").

    ______________________________________                                        Ingredient            %                                                       ______________________________________                                        Nonionic detergent surfactant                                                                       14.0                                                    Sodium carbonate      34.0                                                    Calcium carbonate (80 m.sup.2 /g)                                                                   18.0                                                    Sodium perborate      25.0                                                    Sodium carboxymethylcellulose                                                                       3.3                                                     Fluorescent agent, perfume                                                                          1.0                                                     Water                 4.7                                                     ______________________________________                                    

The bags were found to exhibit improved storage properties under highrelative humidities and to give good detergent properties in use. Thebags of Example 1 and 2 opened within 2 minutes in the wash, the firstby dissolving the polyvinyl alcohol sheet which also formed the seal,and in Example 2 by bursting the bags along a seam. The bags of Example3 did not open in the wash but liberated their contents through thehighly porous polypropylene sheet material after dissolution of thepolyvinyl alcohol sheet, under the vigorous agitation in the washingmachines.

EXAMPLE 4

Sheets of Manila hemp with viscose wet strength agent (21 g/m²) weretreated with an even coating of a water-insoluble polyvinyl acetatehomopolymer obtained from National Adhesives and Resins Limited, Slough,England. The coating material, in the form of an aqueous dispersion, wasspread evenly on one side of each sheet using a cylindrical metal rod.The treated sheets were dried in air. On examination it appeared thatthe coating had penetrated the paper. Bags were prepared from thesetreated sheets by heat sealing, the bags containing 80 g of acarbonate/calcite powder as used in Examples 1 to 3. The bags were41/2"×41/2". None of the bags gave unacceptable dusting during handling.These bags were examined to determine whether the powder was releasedinto the drum of a front loading automatic washing machine afteragitation for 2 minutes. It was found that bags having a coating of 19or 22 g/m² were open and empty after 2 minutes.

EXAMPLE 5

Bags were prepared as in Example 4 above, but containing 60 g of acarbonate/calcite powder containing percarbonate. The bags were storedat 20° C./90% RH together with control bags made of untreated Manilahemp with viscose wet strength agent, provided with a coating ofpolyvinyl acetate on the edges only, for heat sealing purposes. The bagswere examined at weekly intervals to determine whether the coatings hadconferred resistance to degradation on the bag material. The resultswere as follows:

    ______________________________________                                        Weight of coating (g/m.sup.2)                                                                     Time taken to degrade                                     ______________________________________                                         0 (Control)        1 week                                                    19                  3 weeks                                                   22                  2 weeks                                                   37                  3 weeks                                                   40                  4 weeks                                                   ______________________________________                                    

These results show that with this particular coating material a coatingweight of not less than about 19 g/m² gives improved stability againstdegradation.

EXAMPLE 6

Example 5 was repeated with various bag materials and coating materials.Bag material degradation was assessed from the breaking strengths of 1cm wide strips cut from the bags after storage. The results were:

    ______________________________________                                        Bag     Coating   Coating  Storage  Breaking                                  material                                                                              material  weight   time     strength                                  ______________________________________                                        Sausage Clay*     0 g/m.sup.2                                                                            11 days  1041 g                                    casing            29 g/m.sup.2      1189 g                                    (19 g/m.sup.2)    31 g/m.sup.2      1436 g                                                      37 g/m.sup.2      1630 g                                    Sausage Silicone  0 g/m.sup.2                                                                            21 days  NIL                                       casing                                                                        (20 g/m.sup.2)    4 g/m.sup.2        359 g                                    Tea bag           0 g/m.sup.2        37 g                                     paper                                                                         (27 g/m.sup.2)    5 g/m.sup.2        251 g                                    ______________________________________                                         *"Dinkie-A" - Registered Trade Mark.                                     

We claim:
 1. In a detergent product comprising a particulate detergentcomposition contained within a closed water-insoluble water-permeablebag formed of sheet material, the improvement which comprises theprovision of a layer of water-soluble or water-dispersible materialbetween said particulate detergent composition and said sheet materialin an amount effective to protect the bag material from the detergentcomposition and substantially to prevent dusting-out of the detergentcomposition through the sheet material when in a dry state.
 2. Adetergent product according to claim 1, wherein the bag is formed ofpaper, woven, knitted or non-woven fabric or plastics sheet material. 3.A detergent product according to claim 1, wherein the bag is formed of amaterial selected from the group consisting of polyamide, polyester,polyacrylic, cellulose acetate, polyethylene, polypropylene, polyvinylchloride, polyvinylidene chloride and cellulosic fibres and mixturesthereof.
 4. A detergent product according to claim 1, wherein theprotective layer is a continuous layer of water-soluble material.
 5. Adetergent product according to claim 4, wherein the continuous layer ofwater-soluble material is laminated to the sheet material.
 6. Adetergent product according to claim 4, wherein the continuous layer isin the form of a water-soluble bag inside the water-insoluble bag.
 7. Adetergent product according to claim 1, wherein the protective layer isa discontinuous layer of water-soluble material coated on or impregnatedin the sheet material.
 8. A detergent product according to claim 1,wherein the water-soluble material is a synthetic water-soluble polymer.9. A detergent product according to claim 8, wherein the water-solublematerial is soluble polyvinyl-alcohol or polyethylene glycol.
 10. Adetergent product according to claim 1, wherein the water-solublematerial is selected from the group consisting of polysaccharides,alkali metal silicates, soaps and nonionic detergents.
 11. A detergentproduct according to claim 1, wherein the water-soluble material isselected from the group consisting of gelatine, salts or esters ofalginic acid, salts and esters of methyl cellulose, carboxymethylcellulose and water-soluble cationic fabric softeners.
 12. A detergentproduct according to claim 1, wherein the water-dispersible material isa silicone, a fatty acid, a water-insoluble cationic fabric softener,wax or clay.
 13. A detergent product according to claim 1, wherein thethickness of the layer of water-soluble material is between about 15g/m² and about 45 g/m².
 14. A detergent product according to claim 13,wherein the thickness of the layer of water-soluble material is about 30g/m².
 15. A detergent product according to claim 7, wherein the particlesize distribution of the detergent composition, the pore sizedistribution of the sheet material and the thickness of thewater-soluble material layer are such in relation to each other thatless than about 5% of the detergent composition particles can passthrough the pores of the sheet material.
 16. A detergent productaccording to claim 7, wherein the particle size distribution of thedetergent composition, the pore size distribution of the sheet materialand the thickness of the water-soluble material layer are such inrelation to each other that less than about 1% of the detergentcomposition particles can pass through the pores of the sheet material.17. A detergent product according to claim 1, wherein the detergentcomposition is selected from the group consisting of fully formulateddetergent compositions, bleaches, bleach precursors, fabric softeners,starch, perfumes, anti-bacterial agents, anti-static agents, whiteningagents, blueing agents, stain removing agents and mixtures thereof.